System and method for accurate loop length determination in fiber-optic
sensors and signal processors
    31.
    发明授权
    System and method for accurate loop length determination in fiber-optic sensors and signal processors 失效
    光纤传感器和信号处理器的精确环路长度确定的系统和方法

    公开(公告)号:US4768880A

    公开(公告)日:1988-09-06

    申请号:US877321

    申请日:1986-06-23

    IPC分类号: G01D5/353 G01B9/02

    CPC分类号: G01D5/35303

    摘要: A technique and system for accurate determination of differential propagation delays in fiber-optic circuits. The method includes providing a sinusoidally modulated optical signal to each of two waveguides defining optical paths. The optical signals received from the optical paths are combined to form a reference output signal which has a null waveform whenever the propagation delay between the optical signals contains an odd number of half periods of the optical signal waveforms. The difference in the sinusoidal modulation frequency producing a first and second null or constant waveform in the reference signal is determined. This difference value between adjacent frequencies forming the null or constant waveforms comprises the inverse of the difference of signal propagation delay in the two optical paths. Accuracy is improved by measuring the sinusoidal modulation frequencies corresponding to first and second waveforms which are not formed by adjacent frequencies. The difference between those nonadjacent frequencies is divided by the difference in the reference waveform orders of the null reference waveforms to obtain the inverse of the differential propagation delay. Further accuracy is achieved by measuring at least one of the waveform nulls at a high waveform order. Still further accuracy is achieved by monitoring the reference waveforms on a network analyzer and using a frequency synthesizer to more precisely match and identify the modulation frequencies corresponding to the null reference signal waveforms. A system is disclosed for implementing this technique optionally using optical sources having a short coherence length. Mathematical relationships are disclosed for use with measured values in obtaining further improved accuracy.

    摘要翻译: 一种用于精确确定光纤电路差分传播延迟的技术和系统。 该方法包括向定义光路的两个波导中的每一个提供正弦调制光信号。 每当光信号中的传播延迟包含光信号波形的奇数个半周期时,从光路接收的光信号被组合以形成具有零波形的参考输出信号。 确定在参考信号中产生第一和第二无效或恒定波形的正弦调制频率的差异。 形成零波形或恒定波形的相邻频率之间的差值包括两个光路中的信号传播延迟差的倒数。 通过测量对应于不由相邻频率形成的第一和第二波形的正弦调制频率来提高精度。 这些不相邻频率之间的差异除以空参考波形的参考波形次数的差异,以获得差分传播延迟的倒数。 通过以高波形顺序测量至少一个波形零点来实现进一步的精度。 通过监视网络分析仪上的参考波形并使用频率合成器更精确地匹配和识别与空参考信号波形相对应的调制频率,可以进一步提高精度。 公开了一种用于实现该技术的系统,其可选地使用具有短相干长度的光源。 公开了与测量值一起使用的数学关系,以获得进一步提高的准确度。

    Cascaded fiber optic lattice filter
    32.
    发明授权
    Cascaded fiber optic lattice filter 失效
    级联光纤晶格滤波器

    公开(公告)号:US4768850A

    公开(公告)日:1988-09-06

    申请号:US622637

    申请日:1984-06-20

    IPC分类号: G02B6/28 H04L25/03 G02B6/26

    CPC分类号: H04L25/03057 G02B6/2861

    摘要: A fibre optic lattice filter having a transfer function wherein the poles and zeros are adjustable independently of each other. The filter comprises a cascaded configuration of recursive and non-recursive fiber optic lattice filters. In one preferred embodiment, an all-pass fiber optic filter is formed by cascading all-pole and all-zero lattice filters, and by processing the resulting filtered output signal in a subtractive detection system. This detection system produces a signal which represents the difference between two signal outputs provided by the all-zero filter section, and which is adjustable in magnitude, thereby providing an overall filtering function which is capable of handling both positive and negative valued input signals.

    摘要翻译: 一种具有传递函数的光纤格栅滤波器,其中极点和零点彼此独立地调节。 滤波器包括递归和非递归光纤网格滤波器的级联配置。 在一个优选实施例中,全通光纤滤波器通过级联全极点和全零点阵滤波器,并通过在减法检测系统中处理所得到的滤波输出信号来形成。 该检测系统产生一个信号,该信号表示由全零滤波器部分提供的两个信号输出之间的差异,其可在幅度上调节,从而提供能够处理正值和负值输入信号的整体滤波功能。

    In-line fiber optic memory
    33.
    发明授权
    In-line fiber optic memory 失效
    在线光纤存储器

    公开(公告)号:US4738503A

    公开(公告)日:1988-04-19

    申请号:US828782

    申请日:1986-02-12

    摘要: A fiber optic recirculating memory comprises a splice-free length of optical fiber which forms a loop that is optically closed by means of a fiber optic coupler. The coupler couples an optical signal input pulse to the loop for circulation therein, and outputs a portion of the signal pulse on each circulation to provide a series of output pulses. A pump source is included to pump the fiber loop with a pump signal having sufficient intensity to cause stimulated Raman scattering in the fiber loop, and thereby cause amplification of the circulating signal pulse. The fiber characteristics, coupler characteristics, and a pump power are selected to yield a Raman gain which compensates for the total round-trip losses in the fiber loop, so as to provide an output pulse train of constant amplitude pulses. The invention may be implemented utilizing a standard coupler with a pump signal modulation technique. The pump signal is input to the loop as a series of pulses having a duration and a periodicity chosen to prevent overlap of recirculating pump pulses with input pump pulses until at least two circulations of the loop, which minimizes pump power fluctuations and will therefore enhance output signal stability.

    摘要翻译: 光纤再循环存储器包括无接头长度的光纤,其形成通过光纤耦合器光闭合的环路。 耦合器将光信号输入脉冲耦合到环路以在其中循环,并且在每个循环上输出信号脉冲的一部分以提供一系列输出脉冲。 包括泵浦源以用具有足够强度的泵浦信号泵送光纤环,以在光纤回路中引起受激拉曼散射,从而引起循环信号脉冲的放大。 选择光纤特性,耦合器特性和泵浦功率以产生拉曼增益,其补偿光纤环路中的总往返损耗,从而提供恒定幅度脉冲的输出脉冲串。 本发明可以利用具有泵浦信号调制技术的标准耦合器来实现。 泵浦信号作为一系列具有持续时间和周期性的脉冲输入到循环中,以防止循环泵浦脉冲与输入泵浦脉冲的重叠,直到循环的至少两个循环,这最小化泵浦功率波动并且因此将增强输出 信号稳定。

    Fiber optic switch and discretely variable delay line
    34.
    发明授权
    Fiber optic switch and discretely variable delay line 失效
    光纤开关和离散可变延迟线

    公开(公告)号:US4723827A

    公开(公告)日:1988-02-09

    申请号:US628650

    申请日:1984-06-19

    摘要: A single mode optical fiber switch having a base (70) and a laterally slidable top (91). The base is composed of a quartz block (70) with a slight radius of curvature along its length supporting a silicon substrate (66) having a plurality of parallel v-grooves (68). The grooves are fitted with single mode optical fiber segments (64) and lapped to create a flat coupling surface (82) extending laterally across the base. The top (91) is composed of a quartz block with a single v-groove (93) holding a segment of single-mode fiber (95). This fiber (95) is lapped to create a flat coupling surface matable with the coupling surface on the base. The base (70) and top (91) are placed together such that the top fiber (95) may be selectively slid into and out of coupling alignment with any of the fibers (64) in the base (70) to form a discretely variable delay line. A single length of fiber (121) is wrapped around the base ( 70) in helical fashion with each loop being secured in one of the v-grooves (68). By coupling the top fiber (95) with different loops of the base fibers (121), different amounts of delay can be obtained. The delay line can be used to provide variable frequency response for notch and transversal filters.

    摘要翻译: PCT No.PCT / US82 / 01608 Sec。 371日期1984年6月19日 102(e)1984年6月19日PCT PCT卷号1982年11月12日PCT公布。 公开号WO84 / 02005 日期:1984年5月24日。具有基座(70)和横向滑动顶部(91)的单模光纤开关。 基座由石英块(70)组成,石英块(70)沿其长度具有微小的曲率半径,支撑具有多个平行V形槽(68)的硅衬底(66)。 凹槽配有单模光纤段(64)并重叠,以形成横向延伸穿过底座的平坦的耦合表面(82)。 顶部(91)由具有保持单模光纤(95)的单个v形槽(93)的石英块组成。 该纤维(95)被研磨以产生可与基底上的联接表面配合的平坦的联接表面。 基部(70)和顶部(91)被放置在一起,使得顶部纤维(95)可以选择性地滑入和离开与基部(70)中的任何纤维(64)的联接对准,以形成离散变量 延迟线。 单个长度的纤维(121)以螺旋方式围绕基部(70)缠绕,每个环被固定在一个V形槽(68)中。 通过将顶部纤维(95)与基础纤维(121)的不同环耦合,可以获得不同的延迟量。 延迟线可用于为陷波和横向滤波器提供可变频率响应。

    High speed pulse train generator
    35.
    发明授权
    High speed pulse train generator 失效
    高速脉冲发电机

    公开(公告)号:US4652079A

    公开(公告)日:1987-03-24

    申请号:US527163

    申请日:1983-08-26

    摘要: There is disclosed a high speed pulse train generator for generating a train of pulses having arbitrarily close spacing. The apparatus consists of a generator loop comprised of a fiber optic waveguide looped through a directional coupler with the output fiber serving as the input fiber for a similarly structured multiplexer loop. The lengths of the two loops are adjusted such that the time difference in the propagation times of light around the respective loops is small compared to the time of propagation around either loop. The times are adjusted to obtain any arbitrary spacing of the pulses in the output pulse train which is comprised of interleaved pulse trains resulting from each pulse input to the multiplexer loop. Also disclosed is a single loop embodiment for bidirectional data rate transformation and methods of using all the embodiments.

    摘要翻译: 公开了一种高速脉冲串发生器,用于产生具有任意紧密间隔的脉冲串。 该装置包括一个发生器回路,该发生器回路包括一个通过定向耦合器环绕的光纤波导,输出光纤用作类似结构的多路复用器回路的输入光纤。 调整两个环路的长度,使得相对于各个环路周围的光的传播时间的时间差与围绕任一环路的传播时间相比较小。 调整时间以获得输出脉冲串中的脉冲的任意间隔,其由输入到多路复用器环路的每个脉冲产生的交错脉冲串组成。 还公开了用于双向数据速率变换的单回路实施例和使用所有实施例的方法。

    Passive fiber optic multiplexer
    37.
    发明授权
    Passive fiber optic multiplexer 失效
    被动光纤复用器

    公开(公告)号:US4556279A

    公开(公告)日:1985-12-03

    申请号:US319301

    申请日:1981-11-09

    摘要: A passive, frequency selective, fiber optic multiplexer, comprises a directional coupler in which a pair of single mode optical fibers are accurately positioned to provide evanescent field coupling, typically by polishing a portion of the cladding from each of said fibers to place the respective cores of said fibers within the evanescent field of light in the other fiber. The coupling efficiency of a coupler constructed in this manner is wavelength dependent, and provides over-coupling, that is, the capability of transferring light, virtually entirely, back and forth between the fibers within the coupler. The wavelength dependent nature of the evanescent field coupling permits multiplexing, specifically between a pair of wavelengths, one of which is coupled in its entirety from a first fiber to a second fiber, and the other of which is essentially uncoupled. By increasing the number of total transfers of the light signals between the pair of fibers, the frequency resolution of the multiplexer may be optimized for light signals of virtually any frequency separation.

    摘要翻译: 无源频率选择性光纤多路复用器包括定向耦合器,其中一对单模光纤被精确地定位以提供渐逝场耦合,通常通过从每个所述光纤抛光一部分包层以放置相应的芯 的纤维在另一纤维中的消逝光场内。 以这种方式构造的耦合器的耦合效率是波长相关的,并且提供过耦合,即在耦合器内的光纤之间实际上完全传输光的能力。 消逝场耦合的波长依赖性允许多路复用,特别是在一对波长之间进行多路复用,其中一个波长的整体由第一光纤耦合到第二光纤,另一个基本上是耦合的。 通过增加一对光纤之间的光信号的总传输次数,多路复用器的频率分辨率可以针对几乎任何频率间隔的光信号进行优化。

    Fiber optic amplifier
    38.
    发明授权
    Fiber optic amplifier 失效
    光纤放大器

    公开(公告)号:US4553238A

    公开(公告)日:1985-11-12

    申请号:US537493

    申请日:1983-09-30

    摘要: A pair of small diameter optical fibers are arranged in a side-by-side configuration, the first fiber providing a passive guide for pump light, and the second fiber formed of a material, such as Nd:YAG which has amplifying properties at the signal frequency. The signal to be amplified propagates through the second fiber from the active material, resulting in amplification of the signal. The first fiber is pumped from one or both ends, utilizing a cone shaped rod which is optically coupled thereto. A large diameter beam of collimated pump light enters the cone shaped rod, where total internal reflections on the cone walls compress the beam to a small, fiber-size diameter for absorption by the active fiber. The light input to the cone-shaped rod is produced by plural, high power laser diodes, and is collimated by microlenses. By utilizing the cone-shaped rod to couple light from the high power diode lasers to the pump fiber, high pump power densities can be achieved, yielding increased amplification.

    摘要翻译: 一对小直径光纤配置成并排配置,第一光纤提供泵浦光的被动导向器,第二光纤由诸如Nd:YAG的材料形成,该材料在信号处具有放大特性 频率。 要被放大的信号通过第二光纤从活性材料传播,导致信号的放大。 第一纤维从一端或两端泵送,利用光学耦合到其上的锥形杆。 准直泵浦光的大直径光束进入锥形棒,锥形壁上的全部内部反射将光束压缩至较小的纤维尺寸直径,以被有源光纤吸收。 输入到锥形杆的光由多个高功率激光二极管产生,并被微透镜准直。 通过利用锥形杆将来自大功率二极管激光器的光耦合到泵浦光纤,可以实现高泵功率密度,产生增加的放大。

    Stabilized fiber optic sensor
    39.
    发明授权
    Stabilized fiber optic sensor 失效
    稳定光纤传感器

    公开(公告)号:US4530603A

    公开(公告)日:1985-07-23

    申请号:US426887

    申请日:1982-09-29

    摘要: A fiber optic sensor comprises a length of optical fiber, forming a loop, and a fiber optic directional coupler for optically closing the loop. The loop and coupler form a resonant cavity for light circulating therethrough. A PZT cylinder, about which the fiber loop is wrapped, is utilized to control the total round trip phase delay of the circulating light, and thus, control the intensity of the optical output signal. The phase delay is adjusted to a point where the optical output signal is at maximum sensitivity to changes in phase. When the fiber loop is exposed to, e.g., acoustic waves, the loop length changes correspondingly, thereby causing the phase delay, and thus, the optical output signal to vary. By detecting variations in output signal intensity, the frequency and intensity of the acoustic waves may be determined. The sensor also includes a feedback system for stabilizing the fiber loop against low frequency thermal drift.

    摘要翻译: 光纤传感器包括长度的光纤,形成环路,以及用于光学闭合环路的光纤定向耦合器。 环路和耦合器形成用于从其中循环的光的谐振腔。 纤维环绕其缠绕的PZT圆柱体用于控制循环光的总往返相位延迟,从而控制光输出信号的强度。 相位延迟被调整到光输出信号对相位变化具有最大灵敏度的点。 当光纤环路暴露于例如声波时,环路长度相应地改变,从而导致相位延迟,从而导致光输出信号变化。 通过检测输出信号强度的变化,可以确定声波的频率和强度。 该传感器还包括一个反馈系统,用于稳定光纤回路以抵抗低频热漂移。

    Fiber optic rotation sensing interferometer
    40.
    发明授权
    Fiber optic rotation sensing interferometer 失效
    光纤旋转感测干涉仪

    公开(公告)号:US4323310A

    公开(公告)日:1982-04-06

    申请号:US100320

    申请日:1979-12-05

    IPC分类号: G01C19/72 G01P3/36 G01B9/02

    CPC分类号: G01C19/72

    摘要: A fiber optic rotation sensing interferometer based on the Sagnac effect in which mechanical rotation introduces measurable shifts in the phase of optical signals transversing a closed path. The interferometer includes the closed optical path made up of a multi-turn fiber optic loop, a directional coupler or couplers, and an amplifier. A pulse of electromagnetic radiation is fed into the optical path by means of a pulsed electromagnetic source such as a laser and a beam splitter. The beam splitter splits the pulse into two pulses which undergo multiple circulations about the optical path in opposite directions. The directional couplers non-destructively sample the two pulses after each pass therethrough and send the pair of pulse samples to the beam splitter once each circulation. The beam splitter sends these pulse pair samples to a detector and signal processor once each circulation. The detector measures the instantaneous relative phase shift between the two pulse samples in each of the multiple pulse pairs and outputs phase information once each circulation. This phase information is converted by the signal processor into the angle of rotation or into rotation rate of the interferometer.

    摘要翻译: 基于Sagnac效应的光纤旋转感测干涉仪,其中机械旋转引起横向闭合路径的光信号的相位中的可测量偏移。 干涉仪包括由多匝光纤环路,定向耦合器或耦合器以及放大器组成的封闭光路。 通过脉冲电磁源(例如激光和分束器)将电磁辐射的脉冲馈送到光路中。 分束器将脉冲分成两个脉冲,这两个脉冲在相反的方向上绕光路进行多次循环。 定向耦合器在每次通过之后对两个脉冲进行非破坏性采样,每次循环发送一对脉冲样本到分束器。 每次循环后,分束器将这些脉冲对采样发送到检测器和信号处理器。 检测器测量每个多个脉冲对中的两个脉冲样本之间的瞬时相对相移,并在每次循环之后输出相位信息。 该相位信息由信号处理器转换成旋转角度或干涉仪的旋转速率。